You could still use a logical field that supports NULL. The three states would be .T., .F. or .NULL. for unknown which is what NULL is really for anyway.

>Hi Erik,
>
>Your point is well taken. I think you are correct in your assumption about my data not being normalized. Allow me to explain further and you will probably recommend that I should make an attempt at normalization.
>
>I have several categories of medical information data in my record-
>Diseases
>Medications
>Disabilities
>Immunizations
>Allergies
>
>Within each of those categories I have numerous Char 1 Y/N/U (Yes/No/Unknown) fields -
>For example, for diseases I have the following fields:
>Cancer, Hepatitis, Heart Disease, etc.
>For Medications I have fields for the names of medications and so on.
>
>The fields are tied to checkboxes on a form. In other words, Cancer, Hepatitis, Heart Disease each have a Yes and a No checkbox on a form. That's the way the client wanted it. If both the Yes and No checkbox are left blank (unchecked), it means Unknown. I would have preferred a Logical 1 T/F checkbox myself.
>
>I am not sure if normalization would help me out much here. What do you think? Thanks for your thoughts.